At least 50 people have been killed and dozens injured in apparent suicide attack outside an Iraqi police station, hospital officials say.

The truck bomb exploded in the mainly Shia Muslim town of Iskandariya, 40km (25 miles) south of Baghdad, as new recruits were queuing outside.

US troops cordoned off the area to hold back crowds chanting anti-US slogans.

The attack is the latest in a series targeting Iraqis working with the American-led forces in the country.

It comes a day after US officials warned against what they described as an al-Qaeda plot to ignite violence between the majority Shia Muslims and the Sunni Muslims who held power under the former Iraqi regime.